For release: June 13, 2000
EARLY LUNG CANCER DETECTION SAID TO HAVE NO IMPACT ON SURVIVAL
A study of 510 consecutive lung cancer patients showed that detecting the disease at a very early stage when the lesion was small had no effect on survival, according to an article published in the June issue of CHEST.
Writing in the peer-reviewed journal of the American College of Chest Physicians, Edward F. Patz, Jr., M.D., Department of Radiology, Duke University Medical Center, Durham, North Carolina, along with four colleagues, studied 285 men and 225 women (average age 63) who were diagnosed with stage IA non-small cell lung cancer over an 18-year period from 1981 to 1999. Their tumor size was less than 3 centimeters (cm).
According to Dr. Patz, the results of the study suggest that the detection of small nodules does not impact on patient survival. In other words, researchers saw no statistical relationship between tumor size and survival. He commented that it remains to be seen whether detecting smaller nodules with newer technologies such as computerized tomography (CT) scans will alter the natural history of the disease. (The smallest size nodule detectable by CT scan is close to 5 cm.)
According to the researchers, preliminary CT scanning trials showed that up to 30 percent of the small primary lung cancers of the patients had metastasized to regional lymph nodes or distant sites upon initial examination.
During 2000, approximately 177,000 new primary lung cancers will be diagnosed in the U.S. About 25 percent will undergo surgical resection with curative intent.
Lung cancer is the leading cause of cancer-related mortality in both men and women. Approximately 160,000 deaths from the disease occur each year. The disease accounts for 28 percent of all cancer deaths, according to the National Cancer Institute. Most cases occur between the ages of 60 and 80.
"Despite continued advances in diagnostic techniques, treatment protocols, and tumor biology," said Dr. Patz, "the survival rate for lung cancer has shown only minimal improvement over the past several decades. Most patients still present with advanced disease, at which time therapeutic options are less than optimal."
The Duke researchers believe that by the time a lesion has grown to 5 cm, or close to the detectable range of CT scan, the cancer is late in the biology of the disease. According to the investigative team, the exact time at which metastases or genetic change causes the disease to take an aggressive turn has not been well established. They note that research findings suggest that small nodule detection by imaging techniques does not necessarily correspond to the biological behavior of the disease.
William C. Black, M.D., of Dartmouth Medical School, Lebanon, New Hampshire, in an editorial about the Patz et al study, also in the June CHEST, wrote: . . ."the unexpected observations on survival in stage IA lung cancer are timely and provocative. Although they can probably be explained by some combination of chance and confounding, these findings nevertheless force us to think hard about screening with CT and remind us that survival statistics can be misleading. As the authors caution, we should not rush headlong into screening before its effectiveness has been demonstrated by randomized clinical trials or mathematical models that properly account for lead time, over diagnosis, and variations in tumor biology."
According to Dr. Black, lead time refers to the amount of time it takes for a tumor to grow from 1 cm to 3 cm, (2.3 years) at a constant doubling time of 180 days, which should add to survival time. Over-diagnosis is the detection of pseudodisease or false- positives, which can markedly increase reported survival rates. Tumor biology differences assume that there are only two types of lung cancer: aggressive and indolent. Aggressive tumors metastasize when they become 1 millimeter in size, but they remain hidden until they reach 1.5 cm. In contrast, indolent tumors do not metastasize until they reach over 3 cm in diameter. Under those assumptions, IA tumors might be either aggressive or indolent, depending on size, and curable or incurable, depending on metastases stage.
CHEST is published by the American College of Chest Physicians, which represents 15,000 members who provide clinical, respiratory, and cardiothoracic patient care in the U.S. and throughout the world.
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Reporters may wish to contact Kimberly Lynch of the ACCP at (847) 498-8341 for a copy of the article. She can also be reached by fax at (847) 498-5460 or by email at [email protected]. Dr. Patz can be reached by phone at (919) 684-7367 or by fax at (919) 684-7123. His email is [email protected]. Dr. Black can be reached by phone at (603) 650-5846; by fax at (603) 650-5455 ; or by email at [email protected].
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